Jumbo frames not working for ISCSI connections with VMWARE

TrueNAS General
1

Running VMWARE ESXI 7.0

TrueNAS has Mellanox 10gb NIC cards, as well as the ESXI host.

I set:

  1. The VSWITCH(s) set to 9000 MTU
  2. The two interfaces for my ISCSI connection to 9000 MTU (TrueNAS side)
  3. As soon as I put the VMKERNEL to 9000, the ISCSI connection fails.

Ironically I can still ping both ips of the TrueNAS ISCSI NIC cards fine, from the ESXI shell from the host, But the ISCSI traffic is not passing through.

This is insanely frustrating, can someone tell me why this isn’t working?

2

If you are going to use jumbo frames in any application, the ENTIRE path needs to be set to accept them. Have you checked whether your physical network switch your server and storage are connected to can support it at the switch level?
(also, I really haven’t found much in the way of performance with jumbo frames. You may be better off not bothering)